TRI is a government mandated, publicly available compilation of information on the release of nearly 650 individual toxic chemicals and toxic chemical categories by manufacturing facilities in the United States. The law requires manufacturers to state the amounts of chemicals they release directly to air, land, or water, or that they transfer to off-site facilities that treat or dispose of wastes. The U.S. Environmental Protection Agency compiles these reports into an annual inventory and makes the information available in a computerized database. In 2008, 21,695 facilities released 3.9 billion pounds (1.8 billion kilograms) of toxic chemicals into the environment. The total surface water discharges amounted to 246,321,372 pounds (111,729,495 kilograms); while 1,144,615,081 pounds (519,188,667 kilograms) were emitted into the air; 1,786,070,607 pounds (810,148,000 kilograms) were released on-site to land; and 196,339,106 pounds (89,057,920 kilograms) were injected into underground wells. The total amount of toxic chemicals released in 2008 was six percent (257 million pounds [116.5 million kilograms]) lower than the amount released in 2007.